MR16 LEDs for Landscape Lights
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Posted by DocPapsm on June 24, 2008, 9:20 pm
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>>> These seem to be getting better all the time. I'm going to pick up
>>> several different samples to see how well they compare with the >>> halogens for landscape lighting. >
>> That would have been my next suggestion. From what I am reading, they've
>> got a ways to go but for landscaping their "short throw" might not be such >> a >> liability. In your 120F degree end of the world, I'd also want to do some >> serious testing, like what happens if a bulb ends up running accidentally >> when it's full summer daylight shining on them for 8 hours at well over >> 100F. >
I've been using LED's in my landscape lighting for over a year now
>That's a good point. It would probably cause rapid deterioration, and it is >something I will have to protect against. Since they are under X10 control, >it is easy to have the Ocelot watch for a daytime ON, and just switch them >back OFF after a few seconds - leaving them on just long enough for testing. > >Jeff > with great success. They are switched on via an ocelot and a secu16 with an external relay and 12Vdc power supply. A good source for LED's is http://besthongkong.com/ . I've bought from them quite a few times and their shipping, even from Hong Kong, is pretty quick and the quality is pretty good. Haven't seen any other site that can compare to what they offer. I replaced the 7 Watt bulbs (35) in my Malibu lawn lights with the T10 194 LED Inverted Bulbs and light my shrubbery with 12V MR16 Wide with 24 led's also 12Vdc. They really have a lot of LED's for many applications AC and DC. | ||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Manny Bhuta on June 25, 2008, 2:23 am
Please log in for more thread options their service. They have a huge selection. I bought several flexible strips of LEDs from them and made under cabinet lights for my kitchen counter. Manny > A good source for LED's is http://besthongkong.com/ . I've bought from
> them quite a few times and their shipping, even from Hong Kong, is > pretty quick and the quality is pretty good. Haven't seen any other > site that can compare to what they offer. > > I replaced the 7 Watt bulbs (35) in my Malibu lawn lights with the T10 > 194 LED Inverted Bulbs and light my shrubbery with 12V MR16 Wide with > 24 led's also 12Vdc. > > They really have a lot of LED's for many applications AC and DC. | ||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Jeff Volp on June 25, 2008, 10:56 am
Please log in for more thread options Thanks for the recommendation. They do have a lot of options. That 4-watt
unit that quotes 245 lumen output and 150 degree dispersion is especially interesting. (The data sheet gives the lumen output as 100 to 245.) The built-in heat protection addresses my concern about getting too hot on warm summer nights. But, the cost is hard to justify. Running 4 hours a night average would save about 23KWH per year for each bulb. Unless electric rates go way up, that is a long payback period. Jeff >I too have bought from besthongkong.com and have been very satisfied with
>their service. They have a huge selection. I bought several flexible >strips of LEDs from them and made under cabinet lights for my kitchen >counter. > > Manny > >> A good source for LED's is http://besthongkong.com/ . I've bought from
>> them quite a few times and their shipping, even from Hong Kong, is >> pretty quick and the quality is pretty good. Haven't seen any other >> site that can compare to what they offer. >> >> I replaced the 7 Watt bulbs (35) in my Malibu lawn lights with the T10 >> 194 LED Inverted Bulbs and light my shrubbery with 12V MR16 Wide with >> 24 led's also 12Vdc. >> >> They really have a lot of LED's for many applications AC and DC. >
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Posted by amakyonin on June 26, 2008, 6:10 pm
Please log in for more thread options LEDs are all less efficient than halogen lights (of the MR16 type). If
you research them you will find that they all have fewer lumens per watt than any comparable halogen. They are getting close to parity nowadays but they still aren't there yet. Also be aware that some high- output LEDs like the Luxeon-V have a significantly reduced halflife of only 1000 hours. This is much worse than any halogen. When you add in the factor of the price premium for these more exotic lighting systems it doesn't make sense to use them in any application where a halogen will work. The newer Luxeon K2 is the first with a useable lifetime that is long enough to justify the higher cost. If you're still set on going with LEDs, the only option worth considering right now is a lamp with a K2 emitter. Don't buy any lamp that you don't know for certain what type of emitter is used in it. Otherwise, you can't look up its performance on a datasheet. I think that a lot of the misconception that LEDs are more efficient comes from the fact that they don't put out any infrared light that can be felt when you put your hand in front of them. All of the high- output LEDs, however, require significant heat sinking and this is where they dump all of their waste heat to. | ||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Jeff Volp on June 27, 2008, 11:52 am
Please log in for more thread options The DOE CALiPER program summary reports have some very interesting data in
this regard. While I agree that many LED replacement lamps are not competition for MR16 halogens, there are some that are. A table listed 8 lm/W for a 20W halogen, and gave a range up to 13 lm/W for a 60W incandescent. So, illumination efficiency increases as incandescent bulb wattage increases. Reading throughout the latest report, I saw LEDs range from 9 lm/W up to 59 lm/W. So, it would seem that it is certainly possible for LEDs to do much better than halogens. I have received two samples so far. One is a 4W 120V version of a MR16 with 3 high-intensity LEDs. We now have that in a hallway fixture that did have a 25W incandescent. Color temperature is similar (warm white). While incredibly bright, the LED doesn't do quite as well as the incandescent in this wall sconce application because its beam must first bounce off the ceiling, providing indirect lighting. Most of the incandescent light came directly out the side of the sconce. However, for 4W, it certainly does an adequate job in that application. The only real downside is its lack of dimming. That wall sconce lights an otherwise very dark interior hallway. While on 24/7, we normally dim that bulb down to nightlight level at night. Even set to the Leviton minimum 1.6% preset dim level, the LED is still about half its normal intensity. The other sample is a 12V 4W wide-angle 48-bulb MR16. I installed that in a landscape light. While the lighting level is adequate, it is clearly not as bright as the 20W halogen in that application. Its color doesn't do as good a job at bringing out the warm red tones in the crushed red rock we have in our yard. However, considering it uses only 1/5 the energy, I am impressed by how well it works. The CALiPER reports do question the estimated life for LED bulbs. They reported a couple of early failures. And some of the bulbs only make it a small fraction of their projected lifetime. While it is clear to me that some LED bulbs can provide adequate illumination levels for much less energy consumption, the big question is whether their lifespan will be sufficient to actually provide the payback promised. Jeff > LEDs are all less efficient than halogen lights (of the MR16 type). If
> you research them you will find that they all have fewer lumens per > watt than any comparable halogen. They are getting close to parity > nowadays but they still aren't there yet. Also be aware that some high- > output LEDs like the Luxeon-V have a significantly reduced halflife of > only 1000 hours. This is much worse than any halogen. When you add in > the factor of the price premium for these more exotic lighting systems > it doesn't make sense to use them in any application where a halogen > will work. The newer Luxeon K2 is the first with a useable lifetime > that is long enough to justify the higher cost. If you're still set on > going with LEDs, the only option worth considering right now is a lamp > with a K2 emitter. Don't buy any lamp that you don't know for certain > what type of emitter is used in it. Otherwise, you can't look up its > performance on a datasheet. > > I think that a lot of the misconception that LEDs are more efficient > comes from the fact that they don't put out any infrared light that > can be felt when you put your hand in front of them. All of the high- > output LEDs, however, require significant heat sinking and this is > where they dump all of their waste heat to. | ||||||||||||||||||||||||||||||||||||||||||||||
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